Another large part of what has happened to the US middle class is the loss of the kind of manufacturing jobs that allowed many Americans to move into the middle class starting in the post WW2 era. Strong unions, high wages, high demand for ourgoods, etc made the leap up possible for millions. Men could work in a factory, own a house, send their kids to college, etc. Good luck with that today.

Those jobs aren't coming back, no matter who you vote for.